The temporomandibular joint, abbreviated TMJ, is the movable hinge where the maxilla and mandible meet. The temporomandibular joint receives its name from the two bases that meet at this area, the temporal base and the mandible. The joint itself consists of three major bony parts.
The articular eminence is the raised section of the temporal bone that guides the mandible. The glenoidfossa is an oval depression of the temporal base that houses the condyloid process. The condyloid process is the head of the mandible that fits into the glenoid fossa.
The condyloid process articulates with the fossa in the temporal bones to form the temporomandibular joint. The temporomandibular joint has connective tissue and muscle incorporated into its working mechanism, The muscles of mastication assist in holding the TMJ in place.
They also help in the functioning of the joint. The meniscus (also known as the articular disc) consists of tough connective tissue. The disc aids the condyle in sliding along the articular eminence. It fits into the glenoid fossa when the jaw is closed.
The capsular ligament is dense, fibrous connective tissue, which totally encloses the temporomandibular joint. It attaches to the neck of the condyle and the temporal bone. Its functions are in support and protection from trauma.
The movement that occurs when the lower jaw opens causes the condyle to rotate within the glenoid fossa. This movement, called rotational movement, occurs when the jaw opens to approximately two-thirds of its capacity.
As the mandible continues to open, it enters the transitional movement of the temporomandibular joint. During transitional movement, the condyle slides down the articular eminence on the articular disc. This process causes the jaw to move down and forward to create a wider opening.
A condition known as temporomandibular joint syndrome occurs when there is an abnormality within the joint. This condition can include degeneration of the articular disc, eminence, or condyle. More often, it is a result of a combination of several problems. The most severe temporomandibular joint problems must be treated surgically.